Using double or dual horizontal tracks in conjunction with sectional doors has been known to the industry for years. These dual horizontal tracks have been used to decrease the headroom required for operation of sectional doors. For example, one approach provides a sectional door having an upper panel, a top intermediate panel, a bottom intermediate panel, and a lower panel used in combination with dual horizontal tracks, and dual vertical tracks. The dual horizontal tracks include upper and lower horizontal track sections, and the vertical tracks include an inner vertical track section and an outer vertical track section. The lower horizontal track section and the inner vertical track section are interconnected by a curved transition track section to form a roller raceway.
Intermediate rollers provided on the intermediate panels are positioned within the above-discussed roller raceway to allow for articulation of the sectional door between opened and closed positions. Upper rollers are provided in the upper horizontal track section, and lower rollers are provided in the outer vertical track section. The upper horizontal track section and outer vertical track section include track extensions, and the upper rollers and lower rollers are respectively positioned therein when the sectional door is alternately closed and opened. That is, the upper rollers are positioned in the track extension attached to the upper horizontal track section when the sectional door is closed, and the lower rollers are positioned in the track extension attached to the outer vertical track section when the sectional door is opened. As such, the dual horizontal tracks, the dual vertical tracks, and track extensions allow the door panels to be substantially vertical when closed and substantially horizontal when opened, while simultaneously reducing the headroom required for operation.
However, the upper horizontal track section, the lower horizontal track section, the inner vertical track section and the outer vertical track section are separate components, and therefore, must be prepared before installation. To prepare for installation, the horizontal track sections must be joined together, and the vertical track sections must be joined together.
There are different methods for preparing these components for installation with a door. For example, the first method is to preassemble the horizontal track sections together and the vertical track sections together at the factory by mechanical means such as welding, button locking or fasteners. This first method requires labor and equipment for proper assembly, and such labor and equipment is an additional cost to the manufacturer.
A second method is to ship the components separately to the installer, and have the components assembled at the time of installation of the sectional door. This second method passes the costs associated with assembly to the installer, even though it is difficult to properly align the horizontal track sections and the vertical track sections in the field. Therefore, it is more likely for manufacturers to follow the first method of preparing the horizontal track sections and vertical track sections for installation.
Consequently, there is a need for dual track sections that do not require the additional costs of preassembly at the factory or in the field. These track sections should be capable of functioning in sectional door assemblies installed in locations where there is a minimum of space surrounding the frame of a door opening.